In 3GPP (3rd Generation Partnership Project) which is a project aiming to standardize a mobile communication system, it is considered to introduce a new carrier to which a special physical layer specification is applied in addition to a conventional carrier to which a physical layer specification up to Release 11 is applied.
As one of the new carriers, a carrier in which the density of a reference signal is more decreased than a conventional carrier is proposed (for example, see Non Patent Document 1). As a result, a radio resource used for transmitting a reference signal can be used for transmitting user data, etc., and therefore, it is possible to improve throughput.